1. Field of the Invention
The present invention relates to a passenger protection apparatus, which activates a passenger protector to protect a passenger from an impact during vehicle rollover.
2. Description of Related Art
Conventionally, there has been known a passenger protection apparatus, which determines vehicle rollover by a determination whether or not a rollover angular speed produced during vehicle rollover and a rollover angle obtained from the rollover angular speed meet previously defined threshold conditions, respectively, and activates a passenger protector such as a curtain airbag, seatbelt pretensioner, active rollover, etc., if the vehicle rollover is determined (reference to JP-A-2004-42846).
By the way, in the above passenger protection apparatus, a rollover angular speed of a vehicle is detected by an angular speed sensor provided in the vehicle, and the rollover angular speed detected by the angular speed sensor is integrated so as to obtain a rollover angle of the vehicle.
However, if an error (zero-point drift) was observed in an initial setting value during setting the initial value of the angular speed sensor, the rollover angular speed of the vehicle is constantly detected, and the rollover angular speed is always integrated. Thereby, the rollover angle was accumulated.
In this case, it could not determine whether the rollover angular speed of the vehicle to be constantly detected was detected by the error observed during setting the initial setting value of the angular speed sensor or was detected by the vehicle rollover.
Therefore, the accumulated rollover angle met the threshold condition, and the occurrence of the vehicle rollover was determined regardless of the error during setting the initial setting value of the angular speed sensor, resulting in the miss-operation of the passenger protector.